Note:

審題： 註意也有一種情況是： 一共有N個元素，要k個，但有不需要從每一個塊去取， 只需要從其中的一些取。所以這裏end開始應該取最大的element。而且有可能完全取不到，所以start應該從0開始取。剩下的和copy book那道題想法一致。

public class Solution {
    /** 
     *@param L: Given n pieces of wood with length L[i]
     *@param k: An integer
     *return: The maximum length of the small pieces.
     
 
*/
    public int woodCut(int[] L, int k) {
        // write your code here
        if (L == null || L.length == 0) {
            return 0;
        }
        
        int start = 0;
        int end = L[0]; 
        for (int i = 0; i < L.length; i++) {
            if (end < L[i]) {
                end 
 
= L[i];
            }
        }
        
        //System.out.println(end + " " + start);
        
        while (start + 1 < end) {
            int mid = start + (end - start) / 2;
            int tmp = countPiece(L, mid);
            //System.out.println(tmp + " " + start + " " + end + " " + mid);
            if
 
 (countPiece(L, mid) >= k) {
                start = mid;
            } else {
                end = mid;
            }
        }
        
        //System.out.println(start + " " + end);
        
        if (countPiece(L, end) >= k) {
            return end;
        }
        return start;
    }
    
    private int countPiece(int[] L, int maxlen) {
        int count = 0;
        for (int i = 0; i < L.length; i++) {
            count += L[i] / maxlen;
        }
        return count;
    }
}

Wood Cut